The present invention relates in general to thin film electroluminescent displays and is concerned, more particularly, with an improved electroluminescent display having integral thin film resistors associated therewith.
AC electroluminescent thin film displays are fabricated by the successive deposition of several thin film layers on a glass substrate. The display also has patterned electrodes formed by proper mask selection as thin film electrodes, and a protective back glass substrate which is sealed to the base glass substrate by a hermetic seal material usually disposed in the shape of a picture frame. The aforementioned patterned electrodes are typically in the form of two thin films including a transparent front electrode and a rear electrode or counterelectrode. These conducting films extend under the sealing material between the two substrates of glass to the edge of the display where external electrical contact is made. Presently, connection is made externally to series resistors, one per display segment, or connection may be made to electronic multiplexing circuitry. There is thus required, external of the display device, a number of resistors (one per display segment) which adds greatly to the number of separate discrete electronic parts for the entire circuitry associated with the electroluminescent display device. Even in a multiplexing scheme connection is still made to each display segment and although there may be some savings in the number of external resistors required, there is still a requirement for a number of external resistors associated with the display device. Moreover, regardless of the form of segment selection, it is desired to provide optimum current limiting protection, in which case it is desired to have a resistor in series with each segment.